Even for someone like myself, whose instincts are to support the police against the forces of political correctness and health and safety meddling, the case of Jean Charles de Menezes is shocking to the core.

Unprecedented and controversial though yesterday's verdict undoubtedly is, it was surely the only proper one for the jury to deliver.

As Mr Justice Henriques said in his summing up, the police "are not above the law". And the evidence presented to the court clearly showed that there were gross errors in the police operation, the public was put at risk, and a young Brazilian was needlessly killed.

There can be no doubt, now, that the Metropolitan Police is in a most terrible mess.

Far from its anti-terrorist operations being "the envy of the western world", as Met chief Sir Ian Blair bragged just moments before 52 people were butchered on July 7 2005, they have been marked by confusion and mismanagement at the very highest level. And it cost one young man his life.

What has emerged from the Met's trial makes it imperative that if Sir Ian will not stand down then the Home Secretary should have the courage to sack him.

He must be replaced by a policeman who is capable of earning the respect of his troops, restoring their shattered morale and overhauling an institution that has been more concerned with pandering to ethnic grievance-mongers than catching criminals.

For far too long, the Met has been rotting from the top. And that rot must be excised.

The question then must be: What lessons can we learn from this whole sorry episode?

The first is that we must not allow our front-line police to fall prey of the sanctimonious human rights industry which has driven fine officers such as Colonel Tim Collins and Colonel Jorge Mendonca out of the British Army.

Yes, mistakes were made on that terrible day. But the individual officers concerned should be treated with understanding. At a time when our country is in peril from violent Islamists, we need to cherish those who protect us at great personal risk.

We should not forget that the armed police who confronted Mr De Menezes were extraordinarily brave. Two weeks after July 7 and one day after the failed attacks of July 21, they rushed down into the tunnel where they believed a fanatic was about to commit mass murder.

They thought they were risking their lives to save Londoners.

Let's also consider that had Mr De Menezes indeed been a terrorist, and they had failed to prevent him detonating a bomb, they could have been in the dock for failing to protect the lives of the murdered passengers.

I'm glad I don't have to make splitsecond choices like that.

I spent a morning in the Old Bailey last week as an aggressive young barrister sought to nail Commander Cressida Dick for failures in the control room on the day of Mr de Menezes's death.

So gruelling was her interrogation that my companion remarked afterwards: 'Who would want to join the police or the Army these days? How can you do your job if you're looking over your shoulder every minute?'

And yet, when I look back at what happened that day, two things stand out as being unforgivable and indicative of rot at the very heart of the Met.

First, because undercover officers did not arrest Mr de Menezes, a suspected bomber, when he left his home, but instead allowed him to get on to a bus, there was then no safe place for anyone to stop and challenge him.

Why did they not halt him sooner? Because, as a result of over-stretched resources and confusion, there were no firearms officers present to make an armed arrest. And because the culture of the Met is so risk-averse, ordinary police are afraid to do something that isn't part of their job description.

One can blame Government and the health-and-safety culture for some of this, but bad leadership is more to blame. And for that, we can thank the commissioner himself.

Sir Ian Blair is a disaster. A politician first and a policeman second, he has pandered to his masters rather than fighting for his force.

This brings me to the second outstanding conclusion from that tragic day. The higher echelons of the Met had so little trust in their commissioner that in the immediate hours after Mr De Menezes's death, he was the last person in Scotland Yard to know an innocent man had been shot. They either feared or despised him. And who can blame them?

By any reckoning, Sir Ian should have taken charge, demanded to know exactly what had happened.

Instead, he showed no curiosity about events, was kept in the dark by subordinates, and busied himself covering his back with civil servants and with making statements to the press that had no foundation.

Even now, Sir Ian seems to have no grasp of how damaging the revelations about the de Menezes killing has been to the reputation of the Met, and seems perfectly at ease with his own conduct. How else can we explain his incredible behaviour over a £25,000 performance-related bonus?

When he learned that his deputy, Paul Stephenson, had refused to take his bonus, because he felt it inappropriate, Sir Ian accused him of disloyalty. Yet in even seeking the bonus, he neatly demonstrated both his total disdain for public opinion and his utter unsuitability for the post of Britain's most senior policeman.

But then insensitivity is one of Sir Ian's prime characteristics.

This is the man who last year bewildered the inhabitants of crime-infested Haringey by saying local policing was so effective that people could leave their doors unlocked.

It was he who accused the media of giving more coverage to white victims of crime than black and therefore being institutionally racist. He even claimed than "almost no one" could understand why there was so much coverage of the murders in Soham of Jessica Chapman and Holly Wells.

And to cap it all, there was his crassly insensitive claim, the very morning after Mr de Menezes's death, that the Met was "playing out of its socks".

Such pronouncements show just how out of touch Sir Ian is with the very people he is charged with protecting.

What the Metropolitan Police needs is someone who will tackle the deficiencies in the organisation and build on its strengths, someone who demands the highest standards but stands up for his officers against Government meddling.

In short, the force needs someone more interested in leading from the front than covering his own back.

The sooner Sir Ian Blair is replaced the better for the police and the better for London. It wasn't just Jean Charles de Menezes who was let down by Sir Ian Blair's force. We all were.